A typical related-art projector includes a light source which emits substantially white light, an illumination system which equalizes light emitted from the light source and converts the equalized light into polarized light, a color separation system which divides the light having passed the illumination system into lights on three color optical paths, three liquid crystal panels illuminated by the three color illumination lights, a cross dichroic prism which combines respective images entered from the three liquid crystal panels, and a projection lens which enlarges and projects the combined image.
According to this type of projector, a field lens is provided opposed to and in the vicinity of each light entrance surface of the liquid crystal panels such that the illumination system can be telecentric, that is, central light of the illumination light can enter the respective liquid crystal panels in the direction perpendicular to the entrance surfaces of the liquid crystal panels. In addition, a certain type of this projector reduces the enterable angle of illumination light for entering the liquid crystal panel by disposing a concave lens between a superimposing lens and a field lens on a short optical path and a common optical path of the optical paths divided by the illumination system.
[Patent Reference 1] JP-A-2000-241882